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Water Myth , Revisited

January 7, 2011

Straight quote from a recent altitude sickness discussion thread on the Thorntre, from frequent Nepali trekker tomtraveller :

“keep drinking the water, and don’t stop drinking lots the entire time you are at high altitude”
vistet adds “The difference between health and poison is , as in many other cases , a dose question …Pushing large volumes of water only leads to electrolyte imbalance…Taken far enough it can lead to death in cerebral and general edema “

Last fall while trekking Langtang, I met a Norwegian trip leader who was dealing with a very ill trip member. The ill trekker had been experiencing symptom similar, yet different to cerebral edema. Porters carried her down several thousand vertical feet, but her condition did not improve. She was in and out of consciousness. The guide called for a helio evacuation, but the chopper couldn’t arrive until the next morning because of weather conditions. The ill women was placed in a Gamow bag for the night and the trip leader described how difficult it was to keep the bag inflated properly all night, even with a team of people. She was unconscious when she was flown back to Kathmandu and she was in a coma for several days. It turns out that she had drank copious amounts of water, as vistet describes, and she had severely messed up her electrolyte balance. She recovered, and now is ok. But what vistet describes can happen. You need to stay hydrated, but not overly so.

On the less anecdotal side : there are actually a few studies that have gone in the relation between fluid balance and AMS. The Journal of Applied Physiology published a study in 2004 : Early fluid retention and severe acute mountain sickness . The most notable results : the AMS group was the group with lowest urine output , a positive fluid balance and the highest levels of antidiuretic hormone. The non-AMS group was the one with a negative fluid balance , highest urine output and lowest levels of antidiuretic hormone :

“Antidiuretic hormone fell in non-AMS and rose in AMS within 90 min of exposure and continued to rise in AMS, closely associated with severity of symptoms and fluid retention.”

“The extra fluid consumed by both groups just before ascent was rapidly eliminated in non-AMS,.., however, in AMS the elimination of this extra load did not take place.”

Another more practically targeted article in Clinical Journal of Sport Medicine , Exercise Associated Hyponatremia Masquerading as Acute Mountain Sickness , raises the question of how many get sick not in spite of precautions but because of them :

“Vigorous hydration is an unproven yet widely favored maneuver to prevent AMS. Hikers are known to drink copious amounts of fluids until they produce gin clear urine. This is both an unphysiologic and unsafe practice.. In all likelihood, a significant number of hikers and skiers are developing encephalopathy at high altitude with EAH, yet the hyponatremic encephalopathy component of their condition is going unrecognized..”

“Serum sodium below 136 mEq/L should be viewed as abnormal and as a contributing factor to AMS. EAH should be considered the primary cause of encephalopathy if the serum sodium is less than 130 or if symptoms are not improving with conventional therapy”

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2 comments

  1. An article in a NZ magazine says that visitors to Ladakh get more altitude sickness than visitors at other places of the same height, when corrected for other factors. I would be curious to hear more about how the study was done and whether doctors agree before I believe it fully, but anyway, here’s a link:

    http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=10764036

    The most salient part is this:

    “Jean-Paul Richalet, professor of physiology at the University of Paris North, who led the study published in the American Journal of Respiratory and Critical Care Medicine, said: “When adjusted for all other risk factors, especially rate of ascent, one location – Ladakh – remained associated with a higher risk of severe high-altitude illness.”

    But the researchers were unable to identify why the region had the greatest impact. “No clear explanation linked to the climate or the difficulty of the terrain is available, although many informal reports mention the higher risk of this location,” Richalat said.

    The researchers assessed more than 1300 people who planned excursions to mountainous areas which involved at least three days above 4000m and sleeping overnight above 3500m.”

    Another comment that echoes something that Vistet often hints at is this:
    “A common experience at altitude is how breathing fails to keep pace with the demands of the body which triggers involuntary gasps for air and a feeling of suffocation. The study found that those who took most exercise to prepare for their trip were at increased risk from the condition.”


  2. Thanks , really looking forward to reading the full article (“Physiological Risk Factors of Severe High Altitude Illness: A Prospective Cohort Study”). Some more details from the article here : http://www.medicalnewstoday.com/articles/236751.php



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